PIC18 Question: Is it possible to output a binary sequence square wave?

[picbeginner]

Hello,

I am a beginner in PIC programming. I'm using the PIC18F4550 and I've been able to implement a few of the functionalities of PIC microcontrollers, but I was wondering if it was possible to output a binary sequence.

In other words, I got PWM working for 50% duty cycle, so I can get a 10101010 (and repeated) using the CCP/PWM pin...

But is it possible to output something like, 10011101 (and repeated)? I've been browsing the web and I may not be googling the right terms. Only thing that I can think of is to alter the duty cycle constantly.

Is there an easier way?

Thanks!

 

[ronsimpson]

You can load the SPI with 10011101 but how to get to repeat?
Maybe if you connect Dout to Din ....I don't know.

Do you want that pattern or any pattern?
How fast?

 

[be80be]

Bit bang it is about it. It's called bit shift modulation

 

[Pommie]

It depends how fast you want it. If it's a fairly low baud rate (<100k) then it can be done using an interrupt and the PWM module.

Mike.

 

[kubeek]

Not sure how it is with PICs, but with xmega I can use the uart in spi mode with a buffer for tx, so it is possible to output serial data very fast, and still have enough time for the data register empty interrupt to supply new byte. For lower transmit speed it should be possible to make it even without the data buffer.

 

[ChrisP58]

I agree that using a serial output is probably easiest. Either TX from the uart, or SPO from the MSSP/SPI.

Add an interrupt from TX buffer empty to reload the value.

 

[MrDEB]

Just 2 cents worth, what about using a CONST array with the bits arrangerd as you like then just call the array const.